The long-term objectives of the research proposal is to elucidate the mechanism of radiation-induced DNA strand scission. Despite the number of experimental studies on this topic to date, key mechanistic details in the DNA cleavage process are still a point of contention. Though a rigorous theoretical study of intermediates formed under radiative conditions, the relative efficacy of these species as DNA damaging agents and their preferred mode of attack on the deoxyribose moiety of DNA (the direct precursor to strand breakage) will be determined. This study will provide keen mechanistic insight into an area of extreme biomedical significance, as radiation-induced DNA lesions lead ultimately to cell death. In addition, such radiative processes are also used for the treatment of cancer and other diseases.